Su-Monster

Su-monsters are cunning, wicked primates that inhabit forsaken wilderness areas and caves. Adults stand 5 feet tall and have long prehensile tails. Although they can grasp tools and weapons with their tails or clawed feet, su-monsters prefer to rend prey with their claws. Adult su-monsters can also project blasts of psionic energy that leave enemies stunned and unable to flee or defend themselves.
A su-monster sleeps while hanging upside down by its tail. While awake, it can also unleash a devastating attack from that position, rending with all four of its claws.
Su-monsters communicate silently by using their prehensile tails to make gestures. They typically kill more than they can eat, burying the leftovers and marking their location with the victim’s possessions.

Loot.

• 1 Su-Monster Brain (A creature with telepathy can use an action to mentally command the Su-Monster Brain. The brain targets one creature within 30 feet of it. The target must succeed on a DC 11 Wisdom saving throw or take 17 (5d6) psychic damage and be stunned for 1 minute. The stunned target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. Commanding the Su-Monster Brain in this manner causes it to perish.)